A. Field
This invention relates to a card laminate for card-shaped data carriers, in particular smart cards, magnetic strip cards, identity cards and the like, to a card-shaped data carrier produced therefrom, and to methods for production thereof.
B. Related Art
A card laminate for producing card-shaped data carriers consists as a rule of plastic films laminated together. Recesses for receiving electronic components, in particular a chip module, can be formed in the card layers before or after the laminating process. It is also known to embed single components or component groups integrated on card inlays between the card layers—possibly also without such recesses—during the laminating process. Furthermore, security features can be integrated in the laminate or applied to the laminate from outside, for example holograms, magnetic strips, security prints and the like. Special importance is also attached to high-quality printed images with an attractive appearance. It is known in this connection for example to provide outwardly visible layers of the card laminate with a metal layer, print the metal layer and then cover it with a transparent layer for protection against scratching and abrasion. The print against the metallic background has a particularly attractive effect.
Thus, U.S. Pat. No. 4,897,533 describes a credit card with a metal-coated PET film (polyester film) which is first glued to a PVC card core layer by the hot laminating method, then printed on the metal layer and finally protected against scratching by a transparent cover layer. To avoid damage to the printed metal layer upon application of the cover layer, the printed image is first applied to the metal layer by screen printing with a UV-crosslinking printing ink and then the cover layer applied either as a UV-curable varnish or as a polyester film glued on by hot-melt adhesive. The back side of the card core layer can be previously printed and covered with a laminated-on transparent PVC film.
U.S. Pat. No. 6,491,782 B1 describes a card laminate with a similar structure but wherein the card core is constructed of PVC in two layers, namely of a simple PVC film and a PVC-metal layer foil laminate which are each printed on the outer side before being joined together to form the card core. The thus formed card core is in turn covered with transparent cover layers to protect the printed images.
However, printing metallized foils is problematic and as a rule requires previous treatment of the metal areas to be printed with a primer. Such pretreatment is proposed for example in U.S. Pat. No. 6,471,128, making the metal layer suitable for printing both by screen printing and by offset printing. The introduction of the above-mentioned U.S. Pat. No. 6,491,782 B1 furthermore mentions that directly printing the metallized foil surface can be avoided if the foil is printed on the back, but this presupposes that the foil material is transparent.
Printing the metallized foil is problematic since the metallized foil is scratch-sensitive and can be damaged during processing, in particular if the metal coating must be provided with a primer before printing. Rejects due to misprints are likewise to be feared. However, all rejects must be avoided if possible because of the expensive metallized foils.
A further disadvantage of the stated prior art lies in the asymmetrical card layer structure relative to the central plane of the laminate. This can cause undesirable warping to occur during the cooling process after lamination or during later use of the card. A symmetrical structure of the previously described card laminates would involve so many layers, however, that production costs would be uneconomic and the usual ISO standard thickness of 0.76+/−0.08 mm hardly realizable.
The problem of the present invention is therefore to propose a card laminate for card-shaped data carriers and a corresponding card-shaped data carrier as well as methods for production thereof which have a print protected against scratching against a metallic background, the reject rate during production being as low as possible.